Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Radiation-sensitive composition or product
Reexamination Certificate
2002-10-22
2003-08-12
Chapman, Mark A. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Radiation-sensitive composition or product
C399S117000, C399S159000, C399S162000, C399S164000
Reexamination Certificate
active
06605399
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to electrophotographic apparatus and, more particularly, to a novel photoconductive member and to a method of making such a member.
BACKGROUND OF THE INVENTION
The use of an intermediate transfer member in an electrostatographic machine to transfer toner from an imaging member to a receiver (e.g., paper) is well known and is practiced in commercial electrophotographic copiers and printers. A toner image formed on a primary image-forming member (PIFM) is transferred in a first transfer operation to an intermediate transfer member (ITM), and is subsequently transferred in a second transfer operation from the ITM to a receiver. In the second transfer of a toner image from an ITM roller to a receiver, a transfer back-up roller is commonly used behind a paper receiver, a nip being formed to press the receiver to the ITM.
As disclosed by Rimai, et al., in U.S. Pat. No. 5,084,735, and Zaretsky, et al., in U.S. Pat. No. 5,370,961, use of a compliant ITM roller coated by a thick compliant layer and a relatively thin hard overcoat improves the quality of electrostatic toner transfer from an imaging member to a receiver, as compared to a non-compliant intermediate roller. Zaretsky, in U.S. Pat. No. 5,187,526, further discloses that electrostatic transfer can be improved by separately specifying the resistivity of the ITM roller and the transfer back-up roller. Bucks, et al., in U.S. Pat. No. 5,701,567, discloses an ITM roller having electrodes embedded in a compliant blanket to spatially control the applied transfer electric field. Tombs, et al., in U.S. Pat. No. 6,075,965, discloses the use of a compliant ITM roller in conjunction with a paper transport belt in a multi-color electrophotographic machine.
For thermal transfer of toner from a photoconductor to a receiver surface, by Jackson, et al., in U.S. Pat. No. 5,536,609, shows the use of a compliant roller, pad or coating behind a photoconductive belt to assist in the transfer of toner images to a receiving sheet carried by a metal roller. The advantage of the compliant surface behind the photoconductor is that it compresses and widens the nip for good thermal transfer and allows the use of a hard, thermally conductive roller for carrying the receiver paper. Aslam, et al., in U.S. Pat. No. 5,339,146, and Miwa, et al., in U.S. Pat. No. 4,531,825, also suggest an advantage in a compliant surface for a photoconductive member in transferring toner to a heated, hard intermediate transfer member.
The use of a removable endless belt or tubular type of blanket on an intermediate roller has long been practiced in the offset lithographic printing industry, as recently disclosed by Gelinas, in U.S. Pat. No. 5,894,796, wherein the tubular blanket can be made of materials including rubbers and plastics and can be reinforced by an inner layer of aluminum or other metal. As disclosed earlier, for example by Julian, in U.S. Pat. No. 4,144,812, an intermediate lithographic roller comprises a portion having a slightly smaller diameter than the main body of the roller, such that a blanket member can be slid along this narrower portion until it reaches a location where a set of holes located in the roller allow a fluid under pressure, e.g., compressed air, to pass through the holes, thereby stretching the blanket member and allowing the entire blanket member to be slid onto the main body of the roller. After the blanket is located in a suitable position, the source of compressed air or fluid under pressure is turned off, thereby allowing the blanket member to relax to a condition of smaller strain, such strain being sufficient to cause the blanket member to snugly embrace the roller. A sleeve for a printing roller and methods for mounting and dismounting are also disclosed by Hoage et al., in U.S. Pat. No. 4,903,597.
Vrotacoe, et al., in U.S. Pat. No. 5,553,541, discloses a printing blanket, for use in an offset printing press, which includes a seamless tubular elastic layer having compressible microspheres, surrounded by a seamless tubular layer made of a circumferentially inextensible material, and a seamless tubular printing layer over the inextensible layer. It is disclosed that provision of the inextensible layer reduces or eliminates pre-nip and post-nip bulging of the roller when printing an ink image on a receiver sheet, thereby improving image quality by reducing or eliminating ink smearing caused by slippage associated with the formation of bulges in the prior art.
An intermediate transfer roller consisting of a rigid core and a removable, replaceable intermediate transfer blanket has been disclosed by Landa et al., in U.S. Pat. No. 5,335,054, and by Gazit et al., in U.S. Pat. No. 5,745,829, whereby the intermediate transfer blanket is fixedly and replaceably secured and attached to the core. The intermediate transfer blanket, disclosed for use in conjunction with a liquid developer for toning a primary image, consists of a substantially rectangular sheet mechanically held to the core by grippers. The core (or drum) has recesses where the grippers are located. It will be evident from U.S. Pat. Nos. 5,335,054 and 5,745,829 that owing to the presence of the recesses, the entire surface of the intermediate transfer drum cannot be utilized for transfer, which is a disadvantage requiring costly means to maintain a proper orientation of the useful part of the drum when transferring a toner image from a primary imaging member to the intermediate transfer roller, or, when transferring a toner image from the intermediate transfer roller to a receiver. Moreover, the fact that the blanket does not form a continuous covering of the entire core surface, owing to the fact that two of its' edges are held by grippers, is similarly a disadvantage. Another disadvantage arises because there is inevitably a gap between these edges, so that contamination can become deposited there which can lead to transfer artifacts.
Mammino et al., in U.S. Pat. No. 5,298,956, and Mammino et al., in U.S. Pat. No. 5,409,557, both disclose a reinforced seamless intermediate transfer member that can be in the shape of a belt, sleeve, tube or roll and including a reinforcing member in an endless configuration having filler material and electrical property regulating material on, around or embedded in the reinforcing member. The reinforcing member can be made of metal, synthetic material or fibrous material, and has a tensile modulus ranging from about 400,000 to more than 1,000,000 psi (2.8 to more than 6.9 GPa). The intermediate transfer member has a thickness between 2 mils and about 7 mils, and a bulk resistivity less than about 10
12
ohm-cm.
A xerographic printing sleeve mountable on a rigid drum, disclosed by Kuehnle, in U.S. Pat. No. 4,255,508, includes a very thin inorganic photoconductive crystalline compound such as cadmium sulfide coated on a thin metallic sleeve made of a suitable metal, e.g., nickel. The thickness of the photoconductive layer is 200-600 nanometers and is at most of the order of one micrometer. Such a sleeve is not compliant.
An electrostatographic imaging member in the form of a removable replaceable endless imaging belt on a rigid roller is disclosed by Yu et al., in U.S. Pat. No. 5,415,961. The electrostatographic imaging member is placed on the rigid roller and removed from the rigid roller by means involving stretching the endless imaging belt with a pressurized fluid.
An electrostatographic imaging member that includes a photoconductive drum that has inserted therein a compressible sleeve with the composite then being expanded to fit upon a rigid cylindrical core support is disclosed by Swain, in U.S. Pat. No. 5,669,045. The preferred sleeve is a foam that provides substantially no interference fit with the photoconductive drum to facilitate insertion of the sleeve within the drum. However, a relatively large interference fit exists between the rigid core and the sleeve to compress the sleeve as it is expanded by an expandable core. The compression of the sleeve is sufficient to render the electros
Chowdry Arun
Cormier Steven
Grabb Dennis
Herrick Diane M.
May John W.
Chapman Mark A.
NexPress Solutions LLC
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